The present invention relates to refrigerators, and more particularly to a refrigerating system capable of maintaining low temperatures over long periods of time utilizing solely electrical power from solar cells and/or batteries.
Typical refrigeration systems, such as household refrigerators, cold storage systems, and refrigerated vans and railway cars have a continually available power source to maintain the refrigeration compartment at its desired reduced temperature. With such typical systems the power source is readily available and the refrigerating circuit components typically operate a high percentage of the time that the refrigeration system is in use.
Many recreational vehicles, such as power cruisers and motorized mobile homes, require refrigerating systems. These systems are typically expensive in that they must be either provided with an auxiliary power supply or run directly from the power of the vehicle. Such systems are economically feasible for large and expensive mobile homes and power cruisers. However, such systems are not typically available and suitable for the average power cruiser and/or motorized mobile home.
The rapidly accelerating population growth in third world developing and underdeveloped countries is accompanied by the increased difficulty of providing basic medical care for individuals in remote areas. Vast areas of the world do not have electric utility systems which are extensive enough so that vaccines and other perishable medical supplies can be stored and used effectively. As a result, large groups of people are denied the benefits of immunization and treatment for common diseases which have been nearly eliminated in developed countries for many years.
Conventional refrigeration systems are not suitable for maintaining reduced temperatures for any extended period of time without power input. While such systems will normally maintain a low temperature for a few hours, if power is not available very shortly thereafter, the temperature rises and food or medicine spoilage usually occurs. It is generally not possible to operate conventional refrigerators with batteries since an unduly large number of batteries would be required and they would quickly drain, due to the relatively great energy consumption of such refrigerators. In addition, conventional refrigerators are not well adapted for receiving power from solar cells since an unduly large number of such cells would be required to produce the minimum level of electric current needed to operate their compressors.
For these reasons, it is desirable that a refrigeration system be available which requires a very short duration power input and yet has a long duration cooling period between power input periods.